diff options
| -rw-r--r-- | pkg/abi/linux/file.go | 4 | ||||
| -rw-r--r-- | pkg/sentry/syscalls/linux/sys_stat.go | 61 |
2 files changed, 50 insertions, 15 deletions
diff --git a/pkg/abi/linux/file.go b/pkg/abi/linux/file.go index ae33f4a4d..e5a51a9fd 100644 --- a/pkg/abi/linux/file.go +++ b/pkg/abi/linux/file.go @@ -19,6 +19,7 @@ import ( "strings" "gvisor.googlesource.com/gvisor/pkg/abi" + "gvisor.googlesource.com/gvisor/pkg/binary" ) // Constants for open(2). @@ -177,6 +178,9 @@ type Stat struct { X_unused [3]int64 } +// SizeOfStat is the size of a Stat struct. +var SizeOfStat = binary.Size(Stat{}) + // FileMode represents a mode_t. type FileMode uint diff --git a/pkg/sentry/syscalls/linux/sys_stat.go b/pkg/sentry/syscalls/linux/sys_stat.go index 9c433c45d..95f161aac 100644 --- a/pkg/sentry/syscalls/linux/sys_stat.go +++ b/pkg/sentry/syscalls/linux/sys_stat.go @@ -16,6 +16,7 @@ package linux import ( "gvisor.googlesource.com/gvisor/pkg/abi/linux" + "gvisor.googlesource.com/gvisor/pkg/binary" "gvisor.googlesource.com/gvisor/pkg/sentry/arch" "gvisor.googlesource.com/gvisor/pkg/sentry/fs" "gvisor.googlesource.com/gvisor/pkg/sentry/kernel" @@ -124,21 +125,51 @@ func stat(t *kernel.Task, d *fs.Dirent, dirPath bool, statAddr usermem.Addr) err mode |= linux.ModeSocket } - _, err = t.CopyOut(statAddr, linux.Stat{ - Dev: uint64(d.Inode.StableAttr.DeviceID), - Rdev: uint64(linux.MakeDeviceID(d.Inode.StableAttr.DeviceFileMajor, d.Inode.StableAttr.DeviceFileMinor)), - Ino: uint64(d.Inode.StableAttr.InodeID), - Nlink: uattr.Links, - Mode: mode | uint32(uattr.Perms.LinuxMode()), - UID: uint32(uattr.Owner.UID.In(t.UserNamespace()).OrOverflow()), - GID: uint32(uattr.Owner.GID.In(t.UserNamespace()).OrOverflow()), - Size: uattr.Size, - Blksize: d.Inode.StableAttr.BlockSize, - Blocks: uattr.Usage / 512, - ATime: uattr.AccessTime.Timespec(), - MTime: uattr.ModificationTime.Timespec(), - CTime: uattr.StatusChangeTime.Timespec(), - }) + // We encode the stat struct to bytes manually, as stat() is a very + // common syscall for many applications, and t.CopyObjectOut has + // noticeable performance impact due to its many slice allocations and + // use of reflection. + b := make([]byte, 0, linux.SizeOfStat) + + // Dev (uint64) + b = binary.AppendUint64(b, usermem.ByteOrder, uint64(d.Inode.StableAttr.DeviceID)) + // Ino (uint64) + b = binary.AppendUint64(b, usermem.ByteOrder, uint64(d.Inode.StableAttr.InodeID)) + // Nlink (uint64) + b = binary.AppendUint64(b, usermem.ByteOrder, uattr.Links) + // Mode (uint32) + b = binary.AppendUint32(b, usermem.ByteOrder, mode|uint32(uattr.Perms.LinuxMode())) + // UID (uint32) + b = binary.AppendUint32(b, usermem.ByteOrder, uint32(uattr.Owner.UID.In(t.UserNamespace()).OrOverflow())) + // GID (uint32) + b = binary.AppendUint32(b, usermem.ByteOrder, uint32(uattr.Owner.GID.In(t.UserNamespace()).OrOverflow())) + // Padding (uint32) + b = binary.AppendUint32(b, usermem.ByteOrder, 0) + // Rdev (uint64) + b = binary.AppendUint64(b, usermem.ByteOrder, uint64(linux.MakeDeviceID(d.Inode.StableAttr.DeviceFileMajor, d.Inode.StableAttr.DeviceFileMinor))) + // Size (uint64) + b = binary.AppendUint64(b, usermem.ByteOrder, uint64(uattr.Size)) + // Blksize (uint64) + b = binary.AppendUint64(b, usermem.ByteOrder, uint64(d.Inode.StableAttr.BlockSize)) + // Blocks (uint64) + b = binary.AppendUint64(b, usermem.ByteOrder, uint64(uattr.Usage/512)) + + // ATime + atime := uattr.AccessTime.Timespec() + b = binary.AppendUint64(b, usermem.ByteOrder, uint64(atime.Sec)) + b = binary.AppendUint64(b, usermem.ByteOrder, uint64(atime.Nsec)) + + // MTime + mtime := uattr.ModificationTime.Timespec() + b = binary.AppendUint64(b, usermem.ByteOrder, uint64(mtime.Sec)) + b = binary.AppendUint64(b, usermem.ByteOrder, uint64(mtime.Nsec)) + + // CTime + ctime := uattr.StatusChangeTime.Timespec() + b = binary.AppendUint64(b, usermem.ByteOrder, uint64(ctime.Sec)) + b = binary.AppendUint64(b, usermem.ByteOrder, uint64(ctime.Nsec)) + + _, err = t.CopyOutBytes(statAddr, b) return err } |